Head-up display comprising a projection screen and a device for moving and positioning a projection screen, and method for operating such a head-up display

ABSTRACT

The invention relates to a head-up display comprising a projection screen and a device for moving and positioning said projection screen. To open or close the projection screen by the device, a linear movement with a short path can be transformed into a pivoting movement with a long path, an adjustment of the incline of the projection screen being actuatable by means of the device when the projection screen is in the operating position. A method for operating a head-up display comprises actions of a projection screen and a device for moving and positioning a projection screen.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/824,870, entitled “HEAD-UP DISPLAY COMPRISING A PROJECTION SCREEN ANDA DEVICE FOR MOVING AND POSITIONING A PROJECTION SCREEN, AND METHOD FOROPERATING SUCH A HEAD-UP DISPLAY”, filed Jun. 3, 2013, which is anational stage of PCT Application No. PCT/EP2011/066082, filed on Sep.16, 2011, which claims priority from and the benefit of German Patent DE10 2010 046 008.7, filed Sep. 18, 2010. Each of the foregoingapplications is herein incorporated by reference in its entirety.

BACKGROUND

The invention relates to a head-up display comprising a projectionscreen and device for moving and positioning a projection screen. Theinvention further relates to a method for operating such a head-updisplay.

Head-up displays of this type are generally known from prior art andcomprise a display unit with a projection screen onto which vehicleinformation is projected by means of an image-providing unit and, whereapplicable, by means of an optical module. In this instance theprojection screen is of transparent design and located in the field ofvision of the driver of the vehicle.

In its deactivated state, the head-up display is in particularretractable into a cavity within and below the surface of an instrumentpanel of a vehicle and extendable from this cavity when operation isrequired.

Adjustment of an incline of the projection screen about a horizontalincline axis is required, in particular with reference to the height andthe resulting sitting position of the driver of the vehicle, in order toachieve an optimized display distinguished in particular by ageometrically clean and distortion-free presentation of the informationto the driver of the vehicle. To this end, a very fine adjustment isrequired. At the same time, a secure fixing of the projection screen inthe adjusted position is required in order to prevent a positionalchange during the operation of the head-up display.

SUMMARY

The object of the invention is to provide an improved head-up displaywith a projection screen and a device for moving and positioning aprojection screen, and an improved method for operating such a head-updisplay.

With reference to the head-up display, the object is achieved accordingto the invention with a projection screen and a device for moving andpositioning a projection screen.

With reference to the method, the object is achieved according to theinvention with a method for operating a head-up display with aprojection screen and a device for moving and positioning a projectionscreen.

Preferred embodiments and further embodiments of the invention are thesubject matter of the dependent claims.

In the head-up display comprising a projection screen and a device formoving and positioning the projection screen, according to theinvention, in order to extend or retract the projection screen, by meansof the device, a linear movement with a short path can be transformedinto a pivoting movement with a long path, an adjustment of the inclineof the projection screen being actuable by means of the device when theprojection screen is in the operating position. This advantageouslymakes possible a head-up display which is characterized by aparticularly small space requirement and is, at the same time, simple toimplement.

It is particularly advantageous that the extension or retraction of theprojection screen and also an adjustment of the incline of theprojection screen in its operating position are actuatable by means of asingle drive unit.

The device can be moved by means of a drive unit which is embodiedpreferably as a stepper motor.

The drive unit is expediently coupled mechanically to a slide, such thata rotating motion of the drive unit is transformable into a linearmovement of the slide in a guide rail. At least two guide pins arelocated on the slide which project into the guide rail and embody endstops for the slide within the guide rail.

The slide is mechanically coupled to a transformation element by meansof a connecting pin, the connecting pin projecting into a slotted holelocated in the transformation element, and the transformation elementbeing rotatably or pivotably mounted about a fixed first rotation axle.

The transformation element and the base element are preferably rotatablyor pivotably coupled to one another by means of a second rotation axle,the base element being fixedly mounted on the projection screen.

A lever element is rotatably or pivotably coupled advantageously at itsend to the base element by means of a third rotation axle, the leverelement being rotatably or pivotably mounted at its end on the sideremote from the third rotation axle on a fixed fourth rotation axle.

A pin element is located on the end of the second rotation axle, whichpin element, in the operating position of the projection screen, is infunctional connection with the positioning element, with a guidestructure being integrated into the positioning element.

In the operating position of the projection screen, a movement of theslide by means of the drive unit causes a pivoting of the projectionscreen about the rotation axle and a resulting adjustment of the inclineof the projection screen.

In the method for operating a head-up display comprising a projectionscreen and a device for moving and positioning a projection screen,according to the invention, to extend or retract the projection screen,by means of the device, a linear movement with a short path istransformed into a pivoting movement with a long path, an incline of theprojection screen being adjusted by means of the device when theprojection screen is in the operating position. This in particularadvantageously results in only a small space requirement for theintegration of the head-up display into the vehicle. At the same time avery short optical path between the image-providing unit and theprojection screen is feasible. This again results advantageously in animproved image quality of the information displayed on the projectionscreen. In particular, higher levels of sharpness, brightness andcontrast are achieved.

The projection screen in its rest position is, in particular,advantageously located entirely within an instrument panel.

The projection screen in its operating position is expediently moved outof the instrument panel and positioned in such a way that it is locatedin an optical path of the image-providing unit.

DRAWINGS

Exemplary embodiments of the invention are explained in more detail inthe following with reference to drawings, in which

FIG. 1 shows a schematic perspective view of a head-up display accordingto the invention comprising a device for moving and positioning aprojection screen, and

FIG. 2 shows a further schematic illustration of the head-up display.

DETAILED DESCRIPTION

Parts which are identical to one another are shown with the samereference signs in all drawings.

In FIG. 1, a head-up display 1 according to the invention comprising adevice 2 for moving and positioning a projection screen 3 of a head-updisplay 1 is shown in a perspective view. FIG. 2 shows the head-updisplay 1 and the motion sequence of the projection screen 3 in aschematic illustration. The invention is explained in the following withconcurrent reference to both figures.

Apart from the projection screen 3, the head-up display 1 comprises animage-providing unit 4, by means of which the information to bedisplayed is projected onto the projection screen 3. The head-up display1 is preferably mounted in a cavity of an instrument panel of a motorvehicle in a fashion not illustrated, the projection screen 3 beingembodied and located in such a way that it is fully movable. That is tosay that the projection screen 3 is retractable into the cavity belowthe surface of the instrument panel and extendable from this cavity whenthe head-up display 1 needs to be operated. When being extended from thecavity, the projection screen 3 is positioned in such a way that it islocated in an optical path of the image-providing unit 4.

The device 2 is provided for moving the projection screen 3 duringretraction and extension, and for positioning the projection screen 3.

The device 2 comprises a drive unit 5, the drive unit 5 being embodiedin particular as an electric motor, preferably as a stepper motor. Thedrive unit 5 has a rotatable shaft 5.1, in the surface of which areformed screw threads which fully encircle the shaft 5.1.

The shaft 5.1 is coupled to a slide 6 which is located so as to bemovable in the direction of x, the slide 6 comprising a coupling element6.1 with a bore corresponding to the shaft 5.1. Screw threads areembodied within the bore which correspond to the screw threads of theshaft 5.1. The screw threads are located such that a rotation motion ofthe shaft 5.1 about its longitudinal axis results in a linear movementof the slide 6 in a guide rail 7. For the purpose of this guidance, theslide 6 comprises two guide pins 6.2, 6.3, which project into the guiderail 7. At the same time, the guide pins 6.2, 6.3 embody end stops forthe slide 6 within the guide rail 7.

The slide 6 is coupled to a transformation element 8 by means of aconnecting pin 6.4, the connecting pin 6.4 projecting into a slottedhole 8.1 located in the transformation element 8. The transformationelement 8 is rotatably mounted within the head-up display 1 by means ofa fixed first rotation axle R1.

The transformation element 8, in turn, is coupled to a base element 9 towhich the projection screen 3 is mounted. The transformation element 8and the base element 9 are rotatably coupled to one another by means ofa second rotation axle R2.

A lever element 10 is connected to the base element 9 by means of athird rotation axle R3, the lever element 10 being rotatably mounted onthe side remote from the rotation axle R3 on a fourth rotation axle R4,which is fixedly mounted inside the head-up display 1.

During the extension of the projection screen 3, the slide 6 is moved inthe direction of x by means of the shaft 5.1 of the drive unit 5. Inthis context, the transformation element 8, due to its coupling with theslide 6 by means of the connecting pin 6.4, is pivoted about the firstrotation axle R1 such that the linear movement of the slide 6 istransformed into a rotation motion. At the same time, the base element 9is moved in the direction of y along a circular path K, which ispredetermined by means of the lever element 10 being pivotably mountedon the fourth rotation axle R4. This results in the projection screen 3being moved into the optical path of the image-providing unit 4.

When the projection screen 3 and the base element 9 have reached anupper end position, a pin element 11 located on the end of the secondrotation axle R2 engages in a functional connection with a positioningelement 12. The pin element 11 and the positioning element 12 areembodied in such a way that an incline of the projection screen 3 isadjustable through further movement of the slide 6 by means of the driveunit 5. For this purpose, the positioning element 12 comprises a guidestructure which is not illustrated, in which the pin element 11 isguided such that the projection screen 3, when in the upper endposition, is pivoted about the third rotation axle R3. The guidestructure is embodied in such a fashion that the pivoting about therotation axle R3 can be predetermined very precisely, thus enabling theadjustment of incline to be implemented very delicately, steplessly andvery precisely.

The design of the head-up display 1 and the device 2 advantageouslyresults in the extension and the retraction of the projection screen 3from the cavity in the instrument panel and a pivoting of the projectionscreen 3 for the adjustment of its incline being simultaneouslyimplementable despite the very small space requirement of the head-updisplay 1 comprising the device 2. It is furthermore particularlyadvantageous that only the one drive unit 5 is required for this.

1. A head-up display, comprising: a projection screen; a deviceconfigured to move and to position the projection screen, wherein thedevice is configured to transform a first linear movement with a shortpath into a pivoting movement with a long path to extend or retract theprojection screen; wherein the device is configured to move by a driveunit; wherein an adjustment of an incline of the projection screen isconfigured to be actuatable by the device when the projection screen isin an operating position; wherein the drive unit is mechanically coupledto a slide, and wherein a rotating motion of the drive unit isconfigured to be transformed into a second linear movement of the sliderelative to a guide rail; wherein the slide is mechanically coupled to atransformation element by a connecting pin, the connecting pin projectsinto a slotted hole located in the transformation element, and thetransformation element is rotatably or pivotably mounted about a fixedfirst rotation axle; wherein the transformation element and a baseelement are rotatably or pivotably coupled to one another by a secondrotation axle, the base element being fixedly mounted on the projectionscreen; wherein a lever element is rotatably or pivotably coupled at afirst end to the base element by a third rotation axle and rotatably orpivotably mounted at a second end, on a side remote from the thirdrotation axle, on a fixed fourth rotation axle; wherein a pin element islocated on an end of the second rotation axle, and the pin element, inthe operating position of the projection screen, is in functionalconnection with a positioning element, into which a guide structure isintegrated; and wherein, in the operating position of the projectionscreen, the second linear movement of the slide by the drive unit causesa pivoting of the projection screen about the third rotation axle and aresulting adjustment of the incline of the projection screen.
 2. Thehead-up display as claimed in claim 1, wherein the drive unit comprisesa stepper motor.
 3. The head-up display as claimed in claim 1,comprising at least two guide pins on the slide projecting into theguide rail, the guide pins forming end stops for the slide within theguide rail.
 4. A method for operating the head-up display as claimed inclaim 1, wherein to extend or retract the projection screen by thedevice, the first linear movement with the short path is transformedinto the pivoting movement with the long path, wherein the incline ofthe projection screen is adjusted by the device when the projectionscreen is in the operating position.
 5. The method as claimed in claim4, wherein the projection screen in a rest position is located entirelywithin an instrument panel.
 6. The method as claimed in claim 4, whereinthe projection screen in the operating position is moved out of aninstrument panel and positioned in such a way that the projection screenis located in an optical path of an image-providing unit.
 7. A head-updisplay, comprising: a projection screen; a device configured to moveand to position the projection screen, wherein the device is configuredto transform a first linear movement with a short path into a pivotingmovement with a long path to extend or retract the projection screen,the long path is longer than the short path, and the device isconfigured to adjust an incline of the projection screen when theprojection screen is in an operating position; a drive unit configuredto move the device; wherein the device comprises: a slide mechanicallycoupled to the drive unit and a guide rail configured to controlmovement of the slide, wherein a rotating motion of the drive unit isconfigured to induce a second linear movement of the slide relative tothe guide rail; a transformation element mechanically coupled to theslide via a connecting pin, wherein the transformation element comprisesa slotted hole configured to receive the connecting pin, and thetransformation element is rotatably or pivotably mounted about a fixedfirst rotation axle; a base element rotatably or pivotably coupled tothe transformation element via a second rotation axle, wherein the baseelement is fixedly mounted to the projection screen, the secondrotational axle comprises a pin element located on a first end of thesecond rotation axle, and the pin element, in an operating position ofthe projection screen, is in functional connection with a positioningelement, into which a guide structure is integrated; and a lever elementrotatably or pivotably coupled at a first end to the base element by athird rotation axle and rotatably or pivotably mounted at a second end,on a side remote from the third rotation axle, on a fixed fourthrotation axle; wherein, in the operating position of the projectionscreen, the second linear movement of the slide induces a pivoting ofthe projection screen about the third rotation axle and a resultingadjustment of the incline of the projection screen.
 8. The head-updisplay of claim 7, wherein the drive unit comprises a stepper motor. 9.The head-up display of claim 7, comprising at least two guide pins onthe slide projecting into the guide rail, wherein the guide pins formend stops for the slide within the guide rail.
 10. The head-up displayof claim 7, wherein the projection screen is configured to be locatedentirely within an instrument panel when the projection screen is in arest position.
 11. The head-up display of claim 10, wherein theprojection screen is configured to be moved out of the instrument paneland positioned in such a way that the projection screen is located in anoptical path of an image-providing unit when the projection screen is inthe operating position.